1. Field of the Invention
The present invention relates to a FED (field emission display), and in particular to an aging apparatus of the FED and a method thereof.
2. Description of the Related Art
Recently, mobile radio communication such as an IMT-2000 has been spotlighted. The mobile radio communication requires a high quality, a quick speed, a low weight and low power consumption. A MIM (metal insulator metal) is a switching device capable of satisfying the requisites.
In general, the FED has a high vacuum region between an upper plate and a lower plate in which high voltage is applied. Between the upper plate and the lower plate, namely, a high vacuum region is formed between an anode and a cathode in order to emit electrons.
However, in fabrication of a vacuum tube for forming a high vacuum region, contamination may exist on the surface of the tube or an electrode.
If contamination exists in the high vacuum region, when the FED is displayed, electrons having sufficient energy are emitted, the electrons crash against the contamination, and particles of the contamination are separated from the surface of the high vacuum region. When that phenomenon occurs, because a high ionization pressure region is formed in the vacuum, electron emission between a scan electrode and a gate electrode is accelerated, the emitted electrons are not emitted to the anode but overheat a gate electrode.
Afterward, when the gate electrode is overheated, luminance discharge current over an energy gap between a scan electrode and a gate electrode is formed, it may damage the scan electrode severely, and accordingly life span of the FED may be lowered. That phenomenon is called arcing.
In order to prevent occurrence of arcing, there has to be no contamination in the high vacuum region. Accordingly, in the conventional method for eliminating contamination of the MIM FED, substance (getter) for adsorbing contamination is put into the FED to adsorb contamination in operating of the FED.
However, in order to put the substance into the vacuum region between the upper plate and the lower plate, an additional process is required. In addition, the adsorbing substance has a capacity limitation, in particular, capacity of the adsorbing substance is varied according to a size of the MIM FED, because it can not adsorb the contamination over a certain limitation point, still there is a possibility of arcing occurrence. In order to solve the problem, there is a method for eliminating contamination by performing aging.
The conventional aging method for eliminating contamination by using a direct current high voltage will be described.
First, when a direct current high voltage to be gradually increased up to a maximum voltage is applied to an anode, contamination is taken away from the surface of the FED to a vacuum region. Herein, the vacuum state of the FED is maintained not by sealing but by a vacuum pump, and accordingly the contamination is discharged to the outside by the vacuum pump.
Afterward, by applying a voltage to the data electrode and the scan electrode of the FED, electrons are emitted, contamination is taken away again by the emitted electrons, and the contamination is discharged to the outside by the vacuum pump.
However, in the conventional aging method, by applying a direct current high voltage to the FED, lots of energy is consumed. In addition, in the conventional aging method, the FED may be damaged by the inputted lots of energy, and accordingly life span of the FED may be lowered.